Rapid Flow Surveys via Rotating Rake System and Use in Powered Wind Tunnel Models

This paper describes a rotating rake system for rapid measurement of total and static pressure distributions in powered airframe models with complex geometries. The local actuation of the rake rotation mechanism allows access to regions of the flow not easily accessible to traditional traverse systems with wall-mounted leadscrew actuators. Local indexing of the rake pivot to the model precisely positions the rake in the presence of model vibration. The total and static rakes and mechanisms are built from commercially available hardware and materials. The rotating rake system was employed to measure total and static pressures in the propulsive streamtubes of a boundary-layer ingesting powered aircraft model in the NASA Langley 14’×22’ wind tunnel. The specific quantity of interest was the total pressure flux into and out of the propulsors, needed to quantify the power-saving benefits of the boundary layer ingestion system. The paper discusses the benefits and drawbacks of the rotating rake system for the demonstrated wind tunnel experiment and for more general flow measurements.